Based upon studies preformed by the United State military, the number one cause for preventable combat death is one or more extremity hemorrhage. In fact, extremity hemorrhage accounts for approximately 60% of studied preventable combat deaths. When an injured person hemorrhages, hypothermia prevention and management is of critical importance. Hypothermia can lead to cardiac arrhythmias, decreased cardiac output, increased systemic vascular resistance, and most importantly, induced coagulopathy by inhibition of the clotting cascade. If hypothermia is not prevented in this casualty demographic the potential exists that the injured person will not be able to form a clot due to the disruption of the clotting cascade and may potentially bleed to death from an otherwise survivable wounding.
Many wounded personal are given intravenous fluid. Based upon the type of fluid provided, the fluid temperature can much colder than the body temperature and even below 40° F. (4.4° C.). Given that it is recommended that the fluid entering the injured person be at least 98.6° F. (37° C.), it would be advantageous to heat the IV fluid prior to is being delivered to the injured person.
IV fluid heaters or warmers have traditionally been powered by an AC power source because of the high power required to heat IV fluids. The temperature difference between the fluid and the optimal delivery temperature can be as much or even greater than 60° F. (15.5° C.). Battery powered IV fluid warmer have heretofore had poor performance because of the battery sources which have been available.
One known battery-powered blood or IV fluid warmer is marketed as the Thermal Angel® and is produced by Estill Medical Technologies, Inc. having an address of 4144 N. Central Expressway. Suite 260 Dallas, Tex. 75204 and was found on the website http://www.thermalangel.com. The TA-200 model Thermal Angel® device is disclosed as using a 12 volt, rechargeable, lead acid battery weighing 6.25 pounds. This battery requires an external charger and thus requires an extra piece of equipment for operational use. The TA-200 model Thermal Angel® battery has a heating capacity of about 2 to 4 liters of room temperature IV fluid or about 2 to 3 liters of blood. It is understood at this time that the TA-200 model Thermal Angel® battery cannot be charged while the fluid warmer is in use. Further, it is understood that the TA-200 model Thermal Angel® battery has a complete charge time of approximately twelve hours and cannot be fast charged. In addition, The TA-200 model Thermal Angel® battery has only a simplified gauge which is only accurate when the battery is not in use.
Another known battery-powered, IV fluid warmer relates to a lithium polymer (LiPo) battery because LiPo batteries were known to have extremely low internal impedance and to be particularly suitable for high current applications. For example, US Patent Application No. 2007/0105010 A1, to Cassidy, published May 10, 2007 and entitled Lithium Polymer Battery Powered Intravenous Fluid Warmer, discloses such a known LiPo as having a relatively high energy density, no exhibited memory effects, and to be environmentally safe. In particular, the US 2007/0105010 reference also discloses a battery management system for such an IV heater which addresses potential issues with LiPo batteries because they may become dangerous if overcharged or over-discharged and in such circumstances the batteries can explode or catch fire.
Other prior art techniques and devices exist for warming fluids to be infused intravenously into a body, such as a human or other animal. One such conventional device is disclosed in U.S. Pat. No. 5,245,693 (“the '693 patent”). The '693 patent is directed to an intravenous fluid heater that includes a disposable cassette containing a heat exchanger. The preferred embodiment of the heat exchanger disclosed in the '693 patent includes a passageway-defining inner layer sandwiched between a pair of flexible, metal foil membranes. The inner layer defines an extended, e.g., serpentine, path for fluid to be warmed, and serves to space apart and insulate the metal foil membranes from one another. Inlet and outlet ports to the serpentine fluid path are defined in one of the two foil membranes. Heat generated by heating elements which sandwich the heat exchanger is transferred through the metal foil membranes to the fluid flowing through the serpentine path. The heating elements are designed to be graduated, that is, to generate more heat in the area of the inlet portion of the serpentine path than in the area of its outlet.
A yet further disadvantage of the heating arrangement disclosed in the '693 patent is that although means are included for reducing gas bubble formation in the infusion fluid, no means are provided for automatically determining whether such bubbles are present in the fluid or whether there has been reduction in fluid flow rate, and for taking appropriate action (e.g., providing warning and/or stopping fluid flow into the patient) in the event such conditions are determined to be present. As will be appreciated by those skilled in the art, if left unchecked these types of conditions can be, at minimum, deleterious to patient well-being, and at most, life-threatening.
Another conventional infusion fluid warming device is disclosed in U.S. Pat. No. 5,254,094 (“the '094 patent”). In the arrangement disclosed in the '094 patent, a box which may be attached to a patient's arm is provided. Two chambers are included in the box, containing a heat exchanger element constructed from a continuous length of stainless steel tubing in the form of two parallel coils which are connected to each other by a straight length of tubing. The box includes a passage between the chambers such that a warming fluid may be introduced through an aperture in the box into one of the chambers, flow into the other chamber, and then exit the warmer through another aperture in the box. The infusion fluid to be warmed is supplied to the coils through a first flexible plastic inlet tube and discharged for infusion into a patient through a second flexible plastic tube. The warming fluid is supplied via fluid supply tubing to the box from a separate fluid source that is not dimensioned or suitable for being worn by the patient, such as a water heater. A temperature sensor located in the infusion fluid path between the box and the infusion sites may be provided for generating signals indicative of the temperature of the infusion fluid for provision to a microprocessor contained in the same unit comprising the water heater. The microprocessor also receives outputs from a water temperature sensor and controls the water heater, based upon the outputs from these sensors and a desired infusion fluid temperature set by the user, so as to maintain the heating water at a temperature for heating the infusion fluid to the desired temperature.
Disadvantageously, use of a warming fluid/infusion fluid type of heat exchanger, and a warming fluid heater that is remote from the heat exchanger and not wearable by the patient, make '094 patent's arrangement bulky, and relatively difficult to move and set up for use. Also disadvantageously, if even a single crack, pin-hole, imperfect seal, or other opening exists in the infusion fluid tubing/fittings in the heat exchanger, the infusion fluid may become contaminated with the warming fluid.
Other examples of infusion fluid warming prior art are disclosed in U.S. Pat. Nos. 5,381,510, 4,731,072, 3,443,060, 3,475,590, 3,485,245, 3,590,215, 3,614,385, 3,640,283, 3,853,479, 4,038,519, 4,108,146, 4,167,663, 4,293,762, 4,309,592, 4,938,279, 4,847,470, 4,574,876, 3,399,536, 4,962,761, 5,125,069, 4,908,014, 4,906,816, 4,844,074, 4,707,587, 4,759,749, 4,782,212, 4,801,777, 4,680,445, 4,678,460, 4,532,414, 4,464,563, 4,314,143, 4,356,383, and, 4,878,537.
While these and other known devices and technologies offer various advantages and benefits, they also suffer from the aforesaid and/or other disadvantages and drawbacks.
Accordingly, it is an object of the present invention to provide a portable intravenous fluid heater that is light weight with an internal power supply.
It is another object of the present invention to provide a portable intravenous fluid heater that is light weight with an internal power supply that can also use an external power supply.
It is an object of the present invention to provide a portable intravenous fluid heater that includes replaceable internal tubing and inter power supply.